Saturday, 25 June 2011

Last Sunday I have upgraded all firmware in our 2 Blades Enclosure 7000 to the latest release set 9.30. The process itself is not difficult, but it includes many small details and is very important as these blades are production environment, so I decided to write down step by step procedure. I guess it will save my time for the next firmware upgrade, might be helpful for someone of you. I also would like to share couple of problems I encountered during upgrade.

Monday, 6 June 2011

Every time I learn something new about Transparent Page Sharing (TPS) I get the same excitement level I got when I was teenager and was reading science fiction books about future worlds and technologies. So when you finish reading this post ask yourself - How cool is TPS? :)

So what is TPS about?

The main goal of TPS is to save memory and, thus, to give us possibility of providing more memory to your virtual machines than you physical host has. This is called memory overcommitment.

Wednesday, 1 June 2011

In my previous article I quickly went through the main elements and logic of the memory management. You will definitely want to read it before you start reading this article. Today I would like to go deeper into the memory management principles, and particularly of the vSphere memory.

Just to recap the essentials of the previous article - there are 2 main elements of Memory Management Unit (MMU): Page Table Walker and Translate Lookaside Buffer. When an application sends a request to specific memory address it uses Virtual Address (VA) of memory. MMU has to walk through Page Table, find the corresponding Physical Address (PA) translation for VA and put this pair (VA -- PA) to TLB. This will speed up the consequent memory accesses to the same memory address areas. Since Physical Address (PA) of Virtual Machine is still a virtual address there is need to additional translation layer between PA and actual memory address of the ESX host, that is Host Address (HA).